1. Field of the Invention
The present invention relates to a parallax correction system of a small-sized lens shutter camera.
2. Related Background Art
With a nature-oriented trend in recent years, the number of users who make an attempt to take a close shot of flowers has steadily increased. Such users are typically females, middle aged persons, or older persons, and are highly inclined to avoid the use of a relatively large and heavy single-lens reflex camera because of their physical capabilities. Demanded inevitably is a camera capable of a close shot, i.e., having a large image magnification, even in a so-called compact camera where the finder is independent of the photographing lens.
However, in the camera including the independent photographing lens and finder, there arises a problem in which an occurrence of a so-called parallax i.e., a difference between the field of view of the finder and the shot range of the photographing lens in the short distance photography, can not be avoided. For example, referring to FIG. 1, there is produced such a phenomenon that an image to be photographed is displaced, as indicated by the broken line, from the field of view shown by the solid line. This is derived from the fact that the optical axis of the photographing lens is not aligned with the optical axis of the finder. The phenomenon conspicuously appears with a larger image magnification of the photographing lens.
Various proposals have been made for providing a correction of this parallax is a long-standing. One known system is that the optical axis of the finder is inclined interlocking with an extension of the photographing lens, or a field frame of the finder is shifted in accordance with a camera distance. Such a system has been actually incorporated into some cameras and gained a good reputation.
According to the conventional technology, however, the whole or a part of the finder has to be moved mechanically. This inevitably leads to problem in that an internal mechanism of the camera becomes complicated. Therefore, the cameras incorporating the parallax correction system described above are generally expensive.
For an attempt to improve this, there have some proposals to obtain the same effect as moving the field frame mechanically by electrically controlling a size and position of this field frame composed of a liquid crystal plate, etc. In these systems, however, the number of the camera components inevitably increases. Such a parallax correction system can not be incorporated into inexpensive cameras. Further, the parallax correction system functions after measuring a distance to the subject. Hence, the distance to the subject is always measured in order to operate the parallax correction system. In one case is required that the parallax be continuously corrected based on information of distance measurement. In another case impossible, the condition is to complete a series of operations of previously measuring the distance by a half-depression of the shutter and simultaneously extend the photographing lens to correct the parallax before a shutter release.
As explained above, the parallax correction system is not matched with the autofocusing mechanism. The former case, mentioned earlier, undesirably brings about a remarkable rise in the electric power consumed for the camera. The latter case provides a function meaningless to the beginners who do not know a technique about the half-depression of the shutter.